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300

'Piedboeuf Flanging Press.

Plates were formerly flanged entirely by hand, being moulded
on cast-iron forms by blows from wooden hammers, as at Fig. 278.
This method was slow and expensive, and two kinds of hydraulic
presses are now used, (r) the 'PiedboeuP* press for flanging at
one heat, a very effective tool, but requiring separate dies for every
separate kind of work; (2) the universal, or three-ram flanging
machine, invented by Messrs. Tweddell, Platt, Fielding, & Boyd,
and capable of either progressive or single-heat flanging. We will
take these tools in order.

The 'Piedbceuf' Flanging Press, on TweddelPs system, is
shewn at Fig. 289. It consists of an hydraulic cylinder A con-
taining a ram B, which may be raised on the admission of water
pressure, thus lifting the table c, on which is placed the lower
die D. A girder E carries the upper die R, being supported by
guides F F, provided with nuts for the adjustment of E. The girder
G supports the central cylinder A, and four cylinders, H H, con-
taining the 'vice' rams j; and as it is necessary to move the
cylinders H H to varying distances from the centre, the pressure
(or exhaust) pipes are trained through three-quarters of a revolu-
tion between their connections at the pipe circuit K K and those
of the cylinder, so that the pipe is not strained materially when
the positions of H H are changed; in addition there are sheaths,L L
to prevent snapping at the unions. The valve-box M has two
hand levers; N for controlling the vice rams, and P for the
flanging ram. The two dies are shewn ready for flanging a tube
plate Q, which has been made red-hot and laid on the lower
die D. The vice rams are first advanced until the^pjate is held
against the upper die R ; then the flanging ram B is slowly raised
and the plate made to assume the dotted form. The levers being
reversed, the plate may be withdrawn. These, presses are made
large and powerful, but are not used for plates beyond 7 feet
diameter, and rarely up to that

Universal Flanging JPt£$3 (Twedddl's system). — This
very useful machine is sHewix at fj$g. 390. There are two vertical
rams, A acting as vice ram and known as the * elephant's foot,'
and B for flanging the plate on what is tooro^'aiB tl^e ^.^progressive
system.' A third and horizontal ram c gives trie finish, and a